10.2.2 Uncertainties.
The applicant should provide the quantitative uncertainties that are used to develop the normal trajectory dispersions. For each parameter that has a relevant uncertainty, the applicant should provide the functional form of the uncertainty distribution and the numerical parameters that define the distribution. For example, if a parameter has normal uncertainty, the applicant should provide the mean and the standard deviation (the mean should have been used to generate the nominal). If there are correlations between uncertainties in parameters, the applicant should provide data describing these, such as a correlation matrix. The data should be sufficiently annotated that the approach to drawing random sets of the parameters is apparent.
10.3 Worst Atmospheric Conditions.
In accordance with § 450.117(d)(3), the applicant must submit the worst atmospheric conditions under which flight might be attempted, and a description of how the operator will evaluate the atmospheric conditions and uncertainty in the atmospheric conditions prior to initiating the operation. The worst atmospheric conditions should describe the constraints on winds, temperature, or other atmospheric parameters that preclude flight of the vehicle. These typically include constraints on surface level winds, wind shears, or high-altitude winds. The limits may be derived from vehicle structural limits or from limits of the ability of the vehicle to navigate. It may be that the worst conditions vary depending on the mission profile. The applicant may either provide the worst case conditions acceptable for flight under any conditions, or the worst case conditions associated with the representative flight provided below. In either case, the applicant should also describe the process for determining these constraints and how the atmospheric conditions are evaluated during the launch countdown to assess whether the flight may proceed.
10.4 Trajectory Outputs.
The applicant must provide trajectory data developed for a representative trajectory analysis, in accordance with § 450.117(d)(4). A representative trajectory analysis is an analysis that defines a flight to meet the objectives of a specific anticipated mission (e.g.
placing a payload in a particular transfer orbit from a particular launch site). Thus, this should be the same analysis that would be performed in anticipation of that mission.
The applicant should describe the mission objectives and vehicle constraints that are assumed for the representative trajectory analysis. If a flight includes parallel flight segments, nominal trajectory data and both types of normal trajectory sets should be provided for all segments.
10.4.1 Data Specification.
All trajectories submitted with the application must include position, velocity, and orientation, at a maximum of 1 second intervals (1 Hz or greater frequency), in accordance with § 450.117(d)(4). These data are commonly called state vectors, and include the “from operation reference time,” and the three components for each position, velocity, and orientation. Additional data elements for each state vector, such as angular velocity, thrust, vehicle mass, and vacuum IIP location, may also be provided and are encouraged. The timing of key flight events (ignitions, engine shutdown,
23 configuration changes, etc.) in each trajectory should also be provided. No particular file format is recommended, but all trajectory submissions related to an application should be in the same format, and follow the guidance below.
10.4.1.1 Coordinate System Definition.
The applicant should provide a mathematical description of the coordinate system, including units, in which the data is provided. Normally position and velocity are provided in Cartesian coordinates, with coordinate system origin at the center of the Earth or at the launch pad. Orientation of the vehicle is specified as a rotation from the coordinate frame to the vehicle axes, either as Euler angles or a rotation matrix. The coordinate system may either be in an inertial frame or rotate with the Earth. The applicant should specify each of these, including any conventions (left- or righthanded, Euler angle sequence, etc.).
10.4.1.2 File Formats.
The trajectory data should be submitted in a machine-readable format, such as an ASCII text file or a standard spreadsheet file format. For the trajectories, the data should be in tabular form where each record represents a different time of flight and the fields are the elements of the state vector. Extraneous information that would hinder machine processing is discouraged. Event names and times may be included in additional fields of the trajectory files or in separate files. When providing a set of trajectories, it is preferable to provide each trajectory in a separate file, along with an index file describing the purpose of each trajectory.
10.4.2 Nominal Trajectory.
The nominal trajectory required in accordance with § 450.117(d)(4)(i) is the product of the 6DOF analysis with all input data set to the nominal value, per paragraph 8.1 of this AC. In order to ensure consistent interpretation and clear understanding, the applicant should also provide graphics of the nominal trajectory, including:
Present position and the IIP plotted on a map, with times of key events noted;
Range vs. altitude;
Velocity magnitude and geodetic flight path angle vs. time; and Geodetic pitch, yaw, and roll vs. time.
10.4.3 Trajectory Set Characterizing Variability.
The applicant must provide a set of trajectories that characterize variability in the intended trajectory based on conditions known prior to initiation of flight, in accordance with § 450.117(d)(4)(ii). The trajectory data should be the result of the analysis described in paragraph 8.4 of this AC for the same representative mission as used for the nominal trajectory. The trajectories should be clearly labeled to indicate the variability parameters. The applicant should also provide graphical depiction of the
24 trajectories, at a minimum to include present position and IIP on a map, along with times of key events.
10.4.4 Trajectory Set Characterizing Uncertainty.
The applicant must provide a set of trajectories that characterize how the actual trajectory could differ from the intended trajectory due to random uncertainties, in accordance with § 450.117(d)(4)(iii). The trajectory data should be the result of the analysis described in paragraph 8.5 of this AC for the same representative mission as used for the nominal trajectory. These trajectories are typically random samples and are simply indexed by number, but if another scheme is used, the applicant should describe the sampling approach and specify the probability of each trajectory. The applicant may instead submit a covariance matrix (see paragraph 8.5.5 of this AC) provided that the trajectory uncertainty follows a normal distribution. When developing the covariance, times of the random trajectories should be scaled based on event times (see paragraph 8.5.4 of this AC).
OMB Control Number: 2120-0746 (Expiration Date: 08/31/2023)
FAA Form 1320-73 (06-2020)
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